Table 1

Correlation of DTIC N-demethylation with catalytic activities of human P450-selective substrates

DTIC N-demethylation was measured by AIC formation in a panel of 10 human liver microsomes. Triplicate determinations were made for each microsomal preparation. The correlation coefficient (r) was determined from a graph of each P450 catalytic activity versus the mean AIC formation value (pmol/min/mg microsomal protein). Values represent the mean of three experiments.
P450 Formr
7-Ethoxyresorufin O-dealkylation1A20.946
Caffeine N3-demethylation1A20.977
Coumarin 7-hydroxylation2A60.396
Tolbutamide methylhydroxylation2C90.140
5-Mephenytoin 4′-hydroxylation2C190.022
Dextromethorphan O-demethylation2D60.300
Chlorzoxazone 6-hydroxylation2E10.177
Testosterone 6β-hydroxylation3A40.155
Lauric acid 12-hydroxylation4A10.188